title: Analysis of different complexes of type IIa sodium-dependent phosphate transporter in rat renal cortex using blue-native polyacrylamide gel electrophoresis.
abstract: Type IIa sodium-dependent phosphate transporter (NaPi-IIa) can be localized in the apical plasma membrane of renal proximal tubule to carry out a rate-limiting step of phosphate reabsorption. For the apical localization, NaPi-IIa is required to form a macromolecular complex with some adaptor proteins such as Na(+)/H(+) exchanger regulatory factor 1 (NHERF-1) and ezrin. However, the detail of macromolecular complex containing NaPi-IIa in the apical membrane of the renal proximal tubular cells has not been clarified. In this study, we identified at least four different complexes (220, 480, 920, 1,100 kDa) containing NaPi-IIa by using blue-native polyacrylamide gel electrophoresis. Interestingly, LC-MS/MS analysis and immunoprecipitation analysis reveal that megalin is a component of larger complexes (920 and 1,100 kDa). In addition, NaPi-IIa can be heterogeneously co-localized with ezrin and megalin on the apical membrane of renal proximal tubuler cells by fluorescence microscopy analysis. These results suggest that NaPi-IIa can form some different complexes on the apical plasma membrane of renal proximal tubular cells.
authors.affiliation: Department of Clinical Nutrition, Institute of Health Biosciences, University of Tokushima Graduate School, Tokushima, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Tanimura
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Yamada
authors.forename: Akihito
authors.initials: A
authors.lastname: Saito
authors.forename: Mikiko
authors.initials: M
authors.lastname: Ito
authors.forename: Toru
authors.initials: T
authors.lastname: Kimura
authors.forename: Naohiko
authors.initials: N
authors.lastname: Anzai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Horie
authors.forename: Hironori
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Miyamoto
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Taketani
authors.forename: Eiji
authors.initials: E
authors.lastname: Takeda
mesh_terms: D000818:Animals; D002460:Cell Line; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D007672:Kidney Cortex / Q000378:metabolism*; D007687:Kidney Tubules, Proximal / Q000378:metabolism; D026561:Low Density Lipoprotein Receptor-Related Protein-2 / Q000737:chemistry / Q000378:metabolism; D008297:Male; D021962:Membrane Microdomains / Q000378:metabolism; D008970:Molecular Weight; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism; D009893:Opossums; D054730:Protein Interaction Domains and Motifs; D051381:Rats; D017207:Rats, Sprague-Dawley; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa / Q000737:chemistry / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D026561:Low Density Lipoprotein Receptor-Related Protein-2; D046912:Multiprotein Complexes; D050613:Sodium-Phosphate Cotransporter Proteins, Type IIa